The present invention relates to load bearing surfaces, and more particularly to elastomeric load bearing surfaces, such as the seat or back of a chair or bench, or the support surface of a bed, cot or other similar product.
There are continuing efforts to develop new and improved load bearing surfaces. In the context of general load bearing surfaces, the primary objectives of these efforts are to obtain a durable and inexpensive load bearing surface. In the context of seating and other body-support applications, it is also important to address comfort issues. For example, with seating, it can be important to provide a surface that is comfortable and does not create body fatigue over periods of extended use. Given that the load characteristics (e.g. stiffness, resiliency, force/deflection profile) desired in a particular surface will vary from application to application, it is also desirable to have a load bearing surface that is easily tunable for different applications during design and manufacture.
It is known to provide molded load bearing surfaces for a wide variety of applications. For example, molded plastic chairs (e.g. lawn chairs) are available from a variety of well known suppliers. Although these molded chairs provide an inexpensive seating option, they do not provide the level of support and comfort available in more expensive load bearing surfaces, such as conventional cushion sets. Rather, they provide an essentially linear force/deflection profile, which gives the typical molded seating surfaces the feel of a drum or a trampoline. In seating and other body-support applications, this may result in an uncomfortable and sometimes ergonomically unacceptable load bearing surface. Further, the ability to tune the characteristics of a conventional molded seat is relatively limited. Different materials and different material thicknesses can be used to provide a limited degree of control over the characteristics of the seat, but this level of control is not sufficient in many applications.
There is also an increasing use of elastomeric fabrics in the seating industry. Elastomeric fabrics can provide a comfortable, ventilated seating structure. Elastomeric fabrics are typically manufactured from a complex weave of high tech elastomeric monofilaments and multifilament yarns. The process results in a relatively expensive surface. Although elastomeric fabric surfaces can be quite comfortable in many applications, they typically deflect like a sling when a load is applied. Some ergonomic specialists refer to this type of deflection as “hammocking” and consider it undesirable because it can cause the hips to rotate upward. To minimize hammocking, many suspension seats are stretched quite tightly to reduce the amount of deflection that occurs under load. This can reduce the cushion-like feel of the seat making it feel more like a tightly stretched drum. As a result, elastomeric fabrics may not be ideal in all applications.
Accordingly, there remains a need for an elastomeric load bearing surface that is capable of providing non-linear force/deflection profile in response to different loads.